This invention relates generally to filling devices for filling containers; and in particular to a filling device using a zero clearance rotor valve.
Food products that are substantially flowable, such as margarine, butter, sour cream, ice cream, yogurt or the like, typically are packaged in individual containers for retail sale and consumer use. Packaging of these types of food products is ordinarily effected with the use of fill pump devices and associated container conveyors that present containers in a continuous, sequential manner to the filling device which is operated to dispense food product to each of the containers.
In such systems, precise control of the filling device is necessary in order to assure that each container receives the desired quantity of product. In practice, such precision can be difficult to achieve due to inherent fluctuations in product consistency and temperature as well as the periodic start-up and shut-down of a filling line which typically complicates accurate filling of the containers.
Existing filling devices or fillers use a cylindrical, plastic rotor in a cylindrical, stainless steel housing to control the amount of product dispensed to each of the containers. Such fillers require a large clearance between the rotor and the stainless steel housing to allow for thermal expansion of the rotor due to changes in ambient or product temperature. This large clearance allows variable amounts of the metered volume of product to leak back into the supply system during dispensing, which leads to inconsistent fill weights. This clearance also allows product to leak from the supply system to the discharge, causing dripping of product between fills.
As can be readily appreciated, the ability to efficiently internally clean the valve assembly of a filling device is a primary concern when dealing with food products. Known valve assemblies of filling devices ordinarily require substantially complete disassembly to effect internal cleaning of the component parts of the valve assembly. Even frequent internal cleaning of the valve assembly may not properly retard bacterial growth and the like, which could lead to contamination of food product passing through the valve assembly. Disassembly of the valve assembly for cleaning purposes is a time consuming process involving substantial interruption of the production line.
Therefore, there is a need for a product filling apparatus which may be cleaned in place without disassembly. There is further a need for a product filling method and apparatus which permits versatile, dependable operation of a filling system while maintaining the appropriate product weight and appearance under a wide variety of operating conditions.
Products are filled into open containers according to the invention through use of a zero clearance rotor valve combined with a pressure filled metering cylinder. The invention comprises product supply piping, a rotor housing inside which rotates a rotor in zero clearance therewith, a rotor drive mechanism, a metering cylinder inside which moves a piston and a piston drive mechanism. The product supply piping is connected to the top of the rotor housing and the cylinder is connected to one side of the rotor housing. The rotor housing also has an opening on the bottom through which the product flows into the container. The rotor sits inside the rotor housing and has a conical-shaped sealing end with two separate passages or channels cut into it. One passage allows product to flow from the product supply piping into the cylinder. The other passage allows product to flow from the cylinder out to the container when the rotor is shifted (rotated) from a first or prime position to a second or fill position by the rotor drive mechanism. The piston is moved back and forth or reciprocated inside the cylinder by the piston drive mechanism. The location, size and geometry of the passages in the rotor and rotor housing, together with the zero clearance fit, do not allow product to leak from the product supply to either the cylinder or the container.
The conical shape and zero clearance fit of the rotor and rotor housing and the location, size and geometry of the passages in the rotor allow for tight shut off of product. This tight shut off leads to very consistent product fill weights and eliminates leaking of product between fills. The accuracy of the filler is not affected by changes in ambient or product temperature, since the conical sealing surface of the rotor remains in contact with the housing while allowing for expansion.
Moreover, the geometry of the rotor and rotor housing also make this invention easy to clean in place without disassembly. Even though there is operationally a zero clearance between the tapered convex or conical rotor sealing surface of the rotor and its complimentary tapered concave seating surface in the rotor housing, a large clearance between the non-sealing surfaces of the rotor and the rotor housing can be obtained, with a short, backwards movement of the rotor away from the seating surface of the rotor housing. After such movement, all surfaces of the rotor and rotor housing have enough clearance to be cleaned without disassembly. Cleaning solution can flow more easily through the rotor and rotor housing passages, making cleaning faster and more efficient. Cleaning fluid temperatures do not adversely affect rotor motions due to thermal expansion of the components.
The zero clearance sealing surface of the rotor valve also provides an excellent cut-off of product at the end of fill due to the scissor action across the discharge opening in the rotor housing. This allows particles and thick products, such as pieces of fruit, for example, to be cut cleanly without the need for additional cut-off spouting after the rotor valve.